Page text keeps going back to previous states

Before starting posting, I wanted to set up a few pages of permanent writings…

However, after I update and check the published page (which is as expected), I find out sometime later (hours) that all is for naught! My latest updates have reverted to some random previous state and all the work I have done since is gone. Gone! GONE!!! WTF???? GRRRRRRRRRRRRRRR!!!

Since so many people successfully use this site I imagine it to be something I’ve done. Yet, I can’t figure out what it is.